A split coolant circuit as compared to conventional coolant circuit intends that the cylinder head is cooled during the warm-up phase of the combustion engine while the engine block is not initially cooled. This better enables the engine block temperature to be raised more quickly to the operating temperature. A split coolant circuit is one cooling circuit in which the coolant jacket of the cylinder head is separated by suitable means from the coolant jacket of the cylinder block.
In one approach, coolant is conveyed through a cylinder head cooling jacket by a first pump and through a cylinder block cooling jacket by a second pump. Both cooling jackets have no connection within the combustion engine but open on the outlet side into a main circulation conduit system. In another approach the distribution of the coolant flow between the cylinder head and the engine block coolant jacket is fixed based on a threshold temperature of 90° C.
Some of the problems recognized by the inventors with such set-ups come from having a coolant flow distribution such that a portion may be flowed to the cylinder block before the flow is directed to the cylinder head. Further utilizing multiple pumps and/or return passageways may be bulky, thereby reducing the engine's compactness and increasing the size and cost of the engine.
To at least partially address these problems one example includes a split coolant circuit of a combustion engine, comprising a cylinder head coolant jacket having an outlet housing into which an exhaust coolant jacket and an inlet coolant jacket of the cylinder head coolant jacket open, an engine block coolant jacket, a pump delivering coolant to an inlet of the cylinder head coolant jacket without being directly connected to an inlet of the engine block coolant jacket, a radiator, a control element, a heater, a block line, without a block control element, arranged directly on the outlet housing and leading to an inlet side of the engine block coolant jacket, coolant conducted in a same flow direction through the engine block coolant jacket as through the cylinder head coolant jacket, a block return line opening directly into the control element arranged on an outlet side of the engine block coolant jacket, a block shut-off valve arranged in the block return line, a heater line which leads to a cabin heater arranged on the control element, and a heater shut-off valve in a heater return line of the cabin heater. In this way the split coolant circuit comprises one pump reducing engine bulkiness.
In another example, a method for controlling the coolant flow in a split cooling system comprising flowing coolant from a pump to an inlet side of a cylinder head coolant jacket with <5% flowing to a turbocharger in a parallel line, without any connection between the pump and an inlet side of a block coolant jacket and then flowing coolant from the cylinder head coolant jacket to an outlet housing and a control element and then flowing a first coolant portion from the outlet housing through a block line to the inlet side of the block coolant jacket and then to the control element via a block return line such that coolant is directed in a same flow direction as the cylinder head coolant jacket and adjusting a magnitude of the first coolant portion based on an engine temperature via a block shut off valve. This may be done in a manner best suited for the engine operating conditions, providing the benefits of a split cooling circuit which may reduce fuel consumption, reduce emissions and increase the service life of the engine. Further, the coolant flows only through the cylinder head before distribution to other areas occur, better enabling cooling of the hottest engine parts during various engine operating conditions.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.